The number of mosquitoes may seem high, but biologists say no

June 14, 2005

DAWN DE BUSK/Frontiersman reporter

MAT-SU - Bzzz. Whack! Bzzz. Clap! Bzzz. Splat!

Despite the number of successful mosquito kills, many Mat-Su residents come inside from any outdoor activity to discover red welts on their bodies.

Some swear this is the worse year ever to battle the insect some dub "Alaska's state bird."

"The mosquitoes are terrible right now, it doesn't matter where you go," said Lacey Schnoor, Recluse Garden Center's general manager. "A lot of people are commenting on how bad bugs are this year in general - not just mosquitoes, but aphids and caterpillars. It's just the beginning; we'll be dealing with them all summer."

Two years of summers with fewer than usual mosquitoes have spoiled some Alaskans and led them into thinking that the bugs are more plentiful and more aggressive than ever; however, this year's population is probably closer to normal, according to a pest management expert with University of Alaska Fairbanks' Cooperative Extension Services.

"We've had a couple of winters without much snow cover, and a run of cold temperatures, so the insect mortality rate was high," said Fred Sorensen, Integrated Pest Management program coordinator.

Many hibernating insects rely on that blanket of snow to insulate them from freezing air.

"This winter, we had a nice snow cover and a mild winter, so the insects had a good survival rate," he said. The early spring and decent rainfall set up the ideal conditions for a boom in the mosquito population.

"First thing in the spring, people always say the mosquitoes are gigantic," Sorensen said.

Customers coming into the Outdoors & More sporting goods store in Wasilla have said this summer's mosquitoes are abundant and extra large, according to sales employee Ashley Buckwalter, of Big Lake.

"They're annoying," she said.

That first blood-suckers to emerge in the spring are actually adults, an Alaska species called culiseta Alaskanensis, snow mosquito, which spends its winter under leaf litter, in tree stumps or behind tree bark. They kick off the "biting season" in mid- to late-April.

Other species lay eggs in the autumn that face the uncertainty of weather conditions suitable for hatching in the summer. These smaller "youngsters" prove to be more active and agile than their predecessors.

Average rainfall during a warm April and May followed by a warm, dry June creates the perfect environment for mosquito development.

Like an RV's septic system prepped for being stored all winter, the mosquito's body water is replaced with glycerol, which acts as an antifreeze. Another process called supercooling allows the bug to withstand below-freezing temperatures, according to Alaska Science Forum.

Most species of mosquito overwinter as eggs, which can be frozen and still hatch. The insect's life beelines from eggs to larvae or wrigglers, to pupae or tumblers. All of these stages of development occur underwater, which is why swampy land makes an ideal breeding ground. If laid in depressions where water isn't present during the summer months, the mosquito egg could remain dormant for several years, according to Alaska Science Forum.

When the mosquito metamorphoses into an adult, it leaves its aquatic lifestyle behind and takes to the air, becoming a nuisance to humans.

"This year's mosquitoes are more competitive with the higher numbers," Sorensen said. He didn't think it was accurate to say the bugs have become more aggressive than past years'.

"A year difference isn't enough to change the behavior of the mosquito. It has more to do with numbers. They're just doing what they do every year," he said.

Only the female of the species "bites" - using its ovipositor to extract blood. As it extracts blood, the mosquito deposits saliva - which acts as an anticoagulant - into the victim's body. People get the itching and swelling as part of an allergic reaction to the proteins in the mosquito's saliva. Mosquito-borne diseases, such as malaria and the West Nile virus, are also transmitted via saliva.

Not only does the male not bite, but it isn't likely to swarm around humans, Sorensen said. Like butterflies and bees, male mosquitos feed on the nectar of flowers, assisting in the pollination process.

Besides waiting to get bitten, how can people differentiate between male and female mosquitoes?

The female's antennae appear straight, while the male's antennae resemble a feather with little branches used to pick up the scent of the female, Sorensen explained.

The female extracts human blood not to fill its own hunger, but because it needs the protein from warm-blooded animals so its eggs will be viable.

Actually, the instinct to procreate drives the female to hunt for blood. A mosquito's body doesn't manufacture that protein, Sorensen said.

While the female requires the protein from mammal blood to produce her eggs, the mosquito itself serves as a protein snack for newly hatched birds.

"Mosquitoes are a major component of the food chain for swallows, for bats, and for fish," Sorensen said.

In its aquatic stage, the mosquito benefits not only fish, but waterfowl and wading birds like the sandhill crane.

"Mosquitoes have a useful role. Just from circumstantial evidence, it's pretty understandable that since part of a mosquito's life stage is aquatic, a juvenile fish might eat them," Alaska State Fish and Game fisheries biologist Richard Yanusz said. He said he didn't know what percentage of a fish's diet relied on mosquito larvae.

"There are trout and grayling that feed on insects landing on the water or flying low. Juvenille coho salmon are also aggressive feeders," he said.

"My observation at home and out in the field, there's just clouds of mosquitos.

"Anytime, mosquitoes are present like that - near the water - they can be consumed by fish," he said.

Dawn De Busk can be reached at 352-2252, or dawn.debusk@frontiersman.com.